Conventionally, deboning of a dressed carcass halved along the backbone has been performed in the case of a pig or beef cattle such that the dressed carcass halved along the backbone is divided into five blocks, a shoulder, loin, belly, ham, and fillet in a meat processing plant and deboned.
A deboning system of a left or right half block of dressed carcass of a pig, sheep, etc. halved along the backbone is disclosed in Japanese Laid-Open Patent Application No. 10-286057.
As shown in FIG. 8, the system for deboning the shoulder part block of the halved carcass is composed of a preprocessing step 81, picnic shoulder/boston butt separating step 82, bone exposing step 83, shoulder blade removing step 84, bone/meat separating step 85, and boston butt part deboning step 86.
The system is constituted such that the processing on a dressing table is decreased to a minimum, deboning operation is performed while hanging the work (meat block to be deboned), and a series of power-driven supplementary operations and manual operations to mark cuts are combined organically for controlling and retaining of the attitude of the work, exposing of substantial part to be severed, and disjointing of an exposed joint.
A method of deboning a left or right half block of thigh (ham) of a pig halved along the backbone is disclosed in Japanese Laid-Open Patent Application No. 11-056226.
As shown in FIG. 9, the method of deboning consists of an attitude control apparatus 60 for controlling a hanged work including a clamp to hold the work, a pair of left and right cutters 61, a plurality of meat separators 62, and a transfer line 63.
The system is constituted such that the weight of meat is effectively utilized to rip off meat sanitarily from around bones, a plurality of supplementary means using actuators are provided while utilizing gravitational force, and manual operation is limited to marking cuts to relevant parts, thus labor-saving deboning is realized.
Further, in Japanese Laid-Open Patent Application No. 2001-120165 is proposed by the applicant of the present invention apparatuses and a system using the apparatuses for deboning a left or right half block of picnic shoulder/boston butt halved along the backbone of dressed carcass of a pig, etc.
Said disclosure proposes a deboning system of high yield ratio for deboning all over the picnic shoulder/boston butt of a pig, in which deboning is performed automatically for the most part with cuts marked manually only partly.
The system consists, as shown in FIG. 10, of an automatic picnic shoulder/boston butt separating step 65 for separating the boston butt part from the picnic shoulder part after preprocessing of marking cuts is done manually, an cut marking step 66 for marking cuts manually to the remaining shoulder part, an automatic shoulder picnic deboning step 68 including a shoulder blade ripping step 67 executed after the cuts are marked, and a boston butt part deboning step 69 for deboning the boston butt part separated in the step 65.
The boston butt part (work) is transferred in a hanged attitude, size measurements of relevant parts of the work are made at station STa2, STb1, STb7, and STb10 while the work is transferred on a line to determine optimal positions of the work and cutters for the work to be treated, and the work and cutters are moved to the optimal position to debone the work sequentially effectively. Therefore, the deboning can be performed mostly automatically with cuts marked manually only partly.
As mentioned above, the conventional deboning line is constituted such that cuts are marked to the work such as a shoulder part, ham part, etc. of dressed carcass manually to a minimum and the remaining deboning operations such as marking cuts, severing, ripping off of meat or deboned are performed automatically while the work is hanged.
In said automatic deboning operation, it is necessary to separate the boston butt part in order to remove the shoulder blade. To separate the boston butt part from the arm/shoulder block (work) hanged with the end part of the arm being held by a clamp, the attitude of the work is controlled so that the cut surface of the block is on an inclination of 60° to a horizontal plane, the length from the reference position at the end part of the clamp to the lower extremity of the block (work) is measured, and the cutter is moved to a position most suitable for cutting on the basis of the measured length. Particularly, the position to sever and separate the shoulder part from the arm part is determined based on said detected length of the work to minimize the error concerning the separation position due to the difference in size of individual work.
Then, after cuts are marked to the shoulder, upper face of the humerus, side face of the humerus, and right side face of the shoulder blade, and around the shoulder blade of the hanged work, the height position of the shoulder blade (the first reference value for the arm part from the reference position) is measured. Then, the shoulder blade is ripped off in the next step.
Further, the length from the reference position to the end of the humerus (the second reference value for the arm part from the reference position) is measured to prevent disjointing of the joint between the forearm bones and the humerus.
As mentioned above, the work is transferred in a hanged attitude to the apparatus of each step provided along the line, size measurements of the work are made at relevant steps, optimum positions for the work and cutters are determined on the basis of the measurements, the work and cutters are moved automatically to the optimum positions, and deboning operations are performed sequentially.
By the way, the measurement of the length of the work from the reference position (at the lower end part of the clamp) to the lower extremity of the work is necessary when severing the boston butt part, the first reference value indicates the height position of the shoulder blade calculated based on the reference position, and the second reference value indicates the height position of the end of the forearm bones. The measurements are made for eliminating errors concerning the severing position to separate the shoulder part, and the errors are caused by the difference in lengths of the forearm bones and the humerus of individual work. Therefore, if the boston butt part is separated manually beforehand, it becomes unnecessary to measure the length of the work, and the first and second reference value for the arm part.
Particularly, in said automatic deboning system to perform full deboning of a picnic shoulder/boston butt part of a pig after cuts are partly marked manually, a shoulder part of a pig including halved vertebrae and breast bones, a humerus, a shoulder blade, a radius, and a ulna is hung from a platform car, and the forearm bones, humerus, shoulder blade, vertebrae, breast bones, and ribs are deboned. The wagon car is placed on a pair of transfer rails (transfer line), and the wagon car clamps the shoulder part (work) and moves on the transfer line every time processing is completed at every station. The transfer line is formed to be a closed line.
The deboning system is a nearly impeccable system, but there are problems of high cost and large space demanding for installation, and a deboning system suitable for small-to-medium scale food processing factories is expected.